69
8008H–AVR–04/11
ATtiny48/88
10.3.2
Alternate Functions of Port B
The Port B pins with alternate functions are shown in
Table 10-5.
The alternate pin configuration is as follows:
PCINT7 – Port B, Bit 7
PCINT7: Pin Change Interrupt source 7. The PB7 pin can serve as an external interrupt source.
If PB7 is used as a clock pin, DDB7, PORTB7 and PINB7 will all read 0.
CLKI/PCINT6 – Port B, Bit 6
CLKI: External clock input. When used as a clock pin, the pin can not be used as an I/O pin.
PCINT6: Pin Change Interrupt source 6. The PB6 pin can serve as an external interrupt source.
If PB6 is used as a clock pin, DDB6, PORTB6 and PINB6 will all read 0.
SCK/PCINT5 – Port B, Bit 5
SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is enabled as a
Slave, this pin is configured as an input regardless of the setting of DDB5. When the SPI is
enabled as a Master, the data direction of this pin is controlled by DDB5. When the pin is forced
by the SPI to be an input, the pull-up can still be controlled by the PORTB5 bit.
PCINT5: Pin Change Interrupt source 5. The PB5 pin can serve as an external interrupt source.
MISO/PCINT4 – Port B, Bit 4
MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is enabled as a
Master, this pin is configured as an input regardless of the setting of DDB4. When the SPI is
enabled as a Slave, the data direction of this pin is controlled by DDB4. When the pin is forced
by the SPI to be an input, the pull-up can still be controlled by the PORTB4 bit.
Table 10-5.
Port B Pins Alternate Functions
Port Pin
Alternate Functions
PB7
PCINT7 (Pin Change Interrupt 7)
PB6
CLKI (
External clock input)
PCINT6 (Pin Change Interrupt 6)
PB5
SCK (SPI Bus Master clock Input)
PCINT5 (Pin Change Interrupt 5)
PB4
MISO (SPI Bus Master Input/Slave Output)
PCINT4 (Pin Change Interrupt 4)
PB3
MOSI (SPI Bus Master Output/Slave Input)
PCINT3 (Pin Change Interrupt 3)
PB2
SS (SPI Bus Master Slave select)
OC1B (Timer/Counter1 Output Compare Match B Output)
PCINT2 (Pin Change Interrupt 2)
PB1
OC1A (Timer/Counter1 Output Compare Match A Output)
PCINT1 (Pin Change Interrupt 1)
PB0
ICP1 (Timer/Counter1 Input Capture Input)
CLKO (Divided System Clock Output)
PCINT0 (Pin Change Interrupt 0)